This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A053783 #16 Apr 08 2023 16:03:12 %S A053783 1,6,28,140,728,1638,2184,3640,8008,8190,10920,18620,23808,23895, %T A053783 27846,37128,47790,55860,69160,148960,166656,189810,237510,242060, %U A053783 316680,334530,359600,406215,446880,484120,525690,669060,726180,1029952,1078800,1089270,1099170 %N A053783 (1+e)-harmonic numbers: harmonic mean of (1+e)-divisors is an integer. %C A053783 If k = Product p(i)^r(i), d = Product p(i)^s(i) and s(i) = 0 or s(i) divides r(i), then d is a (1+e)-divisor of k. %H A053783 Amiram Eldar, <a href="/A053783/b053783.txt">Table of n, a(n) for n = 1..100</a> %t A053783 f[p_, e_] := (DivisorSigma[0, e] + 1)/(p^e + DivisorSum[e, p^(e - #) &]); aQ[n_] := IntegerQ[n * Times @@ (f @@@ FactorInteger[n])]; Select[Range[10^5], aQ] (* _Amiram Eldar_, Sep 07 2019 *) %Y A053783 Cf. A001599, A049599, A051378, A053784. %K A053783 nonn %O A053783 1,2 %A A053783 _Naohiro Nomoto_, Apr 14 2001 %E A053783 More terms from _Amiram Eldar_, Sep 07 2019